The invention relates to a transmitter having a sensor, which serves for registering a physical parameter and for transducing such into an electrical quantity, a signal pre-processor, which serves for converting the electrical quantity into a raw signal, a signal processor, which serves for converting the raw signal into a measurement signal, and an output stage, which serves for issuing an output signal corresponding to the measurement signal.
In the case of applications common in measurements and control technology, for instance for the monitoring, control and/or automation of complex processes, a multiplicity of transmitters are used, e.g. pressure-, temperature-, flow- and/or fill-level-transmitters.
A transmitter is composed, as a rule, of a sensor, which registers a physical parameter and transduces such into an electrical quantity, and an electronics component, which converts the electrical quantity into a measurement signal, which is then issued by an output stage in the form of an output signal.
The measurement signals are usually registered by a superordinated unit, e.g. a control and/or regulating unit. The superordinated unit delivers, as a function of the instantaneous measurement values, display-, control- and/or regulating-signals for the monitoring, control and/or automating of a process. Examples herefor are programmable logic controllers (PLC), process control systems (PCS) or personal computers (PC).
In the case of conventional transmitters, the physical quantity is registered by the sensor and converted into a raw signal by a signal pre-processor. From the raw signal, the measurement signal is won in a signal processor and fed to an output stage, which issues a corresponding output signal.
In the processing of the pre-processed raw signals, errors can occur, which remain unrecognized in the case of conventional transmitters.
In the transmitters of today, microprocessors are frequently used for signal processing and, for example, for implementing customer-specific transfer functions. When using software, problems can arise e.g. due to hidden software errors, which can lead to erroneous output signals or, in the worst case, even to a freeze-up of the output signal.